Allyl-n-allylcarbamate; n-allylcarbamates



preparing N-substituted carbamates.

.allyl alcohol in the presence of acetonitrile.

United States PatentO ALLYL-N-ALLYLCARBAMATE; N-ALLYLCARBAMATES Richard P. Welcher and Donald W. Kaiser, Old Greenwich, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application January 5, 1954 Serial No. 402,408

7 Claims. or. 260-468) This invention relates to a new and improved method of More particularly it is concerned with a method of preparing N-substituted carbamates using readily available starting materials having a certain molecular structure.

In his copending application Serial 'No. 357,928,'file'd May 27, 1953, now U. S. Patent No. 2,697,720, by Donald W. Kaiser, one of the inventors herein, has disclosed and claimed the compound allyl-N-allylcarbamate. Therein one method for the preparation of the compound is disclosed. The preparation as disclosed therein proceeds by the reactionof potassium cyanate with allyl chloride and The reaction is carried out at elevated temperatures and pressures.

The present invention contemplates difierent starting materials and difierent conditions of reaction in order to produce N-substituted carbamates, allyl N-allyl-carbamate being but one of the carbamates so produced. Tothis end the starting material in the present reaction comprises an iminocarbonate containing a certain carbon group adjacent to at least one oxygen atom. The iminocarbonate is heated to a temperature in the range of about l80500 C. The heat causes the iminocarbonate to rearrange into an N-substituted carbamate. The N-substi tuted carbamate thereby produced is then isolated from the resulting reaction mass.

The iminocarbonate which comprises the starting material of the present invention may be readily prepared by the following general reaction in which an alcohol is reacted with cyanogen chloride in'the presence of a basic acceptor such as sodium hydroxide:

NaOH ZROH CNOl G=NH E10 NaCl The alcohols for the above reaction are readily available. It is generally advisable to prepare the iminocarbonate as needed. On storage these iminocarbonates gradually deteriorate to form the corresponding cyanurate ester and the alcohol.

The iminocarbonate must contain at least one radical which contains the carbon group:

This radical must be attached to at least one oxygen atom in the iminocarbonate. It will be recognized that the above carbon group is the basic structure found in the allyl radical. However, this same carbon group also ocours in the l-cyclohexenylmethyl radical.

2,819,292 Patented Jan. 7, 1958 lCC and inthe alcyclohexenyl radical I methyl, ethyl, propyl, isopropyl, butyl, amyl, isoamyl, hexyl, heptyl, octyl, nonyl, decyl, and others; they may be attached to alkenyl radicals, for example, allyl, crotyl, ethallyl, pentenyl, hexenyl, heptenyl, octenyl,'and others; they may be attached to aralkyl radicals such as benzyl, phenylethyl, and others; they may be attached to aralkenyl radicals such as alpha-phenyleallyh The heating of the iminocarbonate necessary to cause the rearrangement to the N-substituted carbamate should be done rapidly and maintained for a short period of time.

This may be done by passing the imino'carbonatedropwise down a hot tube.

The reaction mass may be collected in a vessel at the bottom of the hot tube. As an alternative method, a film of the iminocarbonate may be deposited on a heated spinning plate or on a vertical column. The product maybe collected as it is flung oft the periphery of the wheel or as. it collects at the bottom of the column. On fractionation the N-substituted carbamate may be recovered from the collected reaction mass. The-residence time in the hot tube or on a spinning plate should generally be in the range of about 0.1- 15 seconds.

It is generally preferred to maintain a residence time of be mixed withrthe iminocarbonate before or during heat- The rearrangement is carried out at a temperature in the range of about l500 0.. Generally, if the higher temperatures are used then theresidence time should be shorter. For instance, if a temperature of. about 500 C. is to be used,'residence time should be onthe order of about 0.1 seconds, particularly if an N-allylcarbamate is being made. If, however, the temperature to be used is 180 C., the residence time may be appreciably longer. The preferred temperature range is 380-420 C. since at this temperature range a residence time of about 0.5 second suilices to cause the rearrangement using a hot tube of convenient size. A temperature of 400 C. and a residence time of 0.5 second are readily obtained in the laboratory and plant. In any case, recycling the reaction mass may occasionally be desirable.

The reaction of the present invention may be illustrated by the following equation:

H C=NH -v BNHCOR' comonomers with such things as styrene to form useful resins. These compounds can also be hydrolyzed to obtain the amines which would be expensive to produce by some other method.

In order that those skilled in the art may better understand how the present invention can be carried into efiect, the following examples are given by way of illustration and not by way of limitation.

Example 1 A glass tube 18 inches long, 1 inch in diameter, wound with resistance wire and fitted with a thermocouple, dropping funnel, gas inlet, and a receiver at the bottom was heated to 400 C. and flushed with nitrogen gas. Diallyl iminocarbonate (84 parts) was added dropwise over a period of 2.1 hours. On fractionation the reaction mass (82 parts) yielded allyl N-allylcarbarnate (68 parts), B. P. 7780 C./mm., n =1.4583, corresponding to 81% overall yield. Its identity was confirmed by its infrared spectrum. Other products were allyl alcohol and resin.

Example 2 A total of parts di-Z-methallyl iminocarbonate were dropped through the glass tube described in Example 1 over a period of 1 hour. The temperature was 380 C. The reaction mass (38 parts) on fractionation gave 35 parts of 2-methallyl N-Z-methallyl-carbamate correspond ing to an overall yield of Example 3 parts of di-S-methallyl iminocarbonate were dropped through the hot tube of Example 1 over a period of 2.5 hours. The temperature was 400 C. The reaction mass (87 parts) was fractionated. This yielded 78 parts of 3-methallyl N-l-methallyl carbamate, an overall yield of 78%.

Example 4 87 parts of di (A cyclohexenyl) iminocarbonate were dropped through the hot tube of Example 1 over a period of 6 hours. The temperature was about C. The reaction mass of 78 parts was fractionated to give 34 parts of A -cyclohexenyl N-A -cyclohexeny1 carbamate, a yield of 39%.

Example 5 42 parts of di(1-cyclohexenylmethyl) iminocarbonate were dropped through the hot tube of Example 1 over a period of 0.5 hour. The temperature was 500 C. The

reaction mass of 39 parts was fractionated to give 37.5 parts of l-cyclohexenylmethyl N-2-methyl-A -cyclohexenyl carbamate.

We claim:

1. The method of preparing an N-substituted carbamate ester which comprises heating an iminocarbonate containing two like carbon groups having the formula each group being adjacent to at least one oxygen atom to a temperature in the range of about 180-500 C., and recovering N-substituted carbamate ester thereby produced from the reaction mass.

2. The method of preparing an N-allylcarbamate ester which comprises heating a diallyl iminocarbonate to a temperature in the range of about 180500 C., and recovering N-allylcarbamate ester thereby produced from the reaction mass.

3. The method according to claim 2 wherein said heating is carried out at a temperature range of about 380- 420 C.

4. The method according to claim 3 wherein said heating is carried out at about 400 C.

5. The method for preparing allyl N-allylcarbamate which comprises heating di-allyl iminocarbonate to a temperature of about 400 C. for a period of about 0.5 second, and recovering allyl N-allylcarbamate thereby produced from the reaction mass.

6. The method of preparing 1-cyclohexenylmethyl N-2- methyl-a -cyclohexenyl carbamate which comprises heating di(1-cyclohexenylmethyl) iminocarbonate to a temperature of about 500 C., and recovering I-cyclohexenylmethyl N-2-methyl-A -cyclohexenyl carbamate from the 0 reaction mass.

References Cited in the file of this patent UNITED STATES PATENTS Kropa June 3, 1952 Kaiser Dec. 21, 1954 OTHER REFERENCES Chapman: Chem. Abs. 20, 181 (1926). 

1. THE METHOD OF PREPARING AN N-SUBSTITUTED CARBAMATE ESTER WHICH COMPRISES HEATING AN IMINOCARBONATE CONTAINING TWO LIKE CARBON GROUPS HAVING THE FORMULA 